In the future fifth-generation mobile communication technology, a wireless communication network is evolving towards the direction of network diversification, broadband, synthesis and intelligence. With the popularization of various intelligent terminals, a data flow may increase in a spurt manner. Data traffic is mainly distributed in indoor and hot spots in the future. In this case, a large number of small cells may be deployed to adapt to increasing requirements of data traffic. For example, the concept of small cell is introduced in the Long Term Evolution (LTE) Release 12. Compared with a macro cell having a coverage range of a few kilometers, the small cell has a smaller coverage range, which generally may cover an indoor range of 10 meters or an outdoor range of 2 kilometers. And a small base station may operate in an licensed frequency spectrum and an unlicensed frequency spectrum.
In addition, in the fifth-generation mobile communication technology, the License Assisted Access (LAA) as technology for expanding the Long Term Evolution (LTE) to unlicensed frequency bands has become a research focus. For example, the research project of directly using the unlicensed frequency bands in LTE, i.e., LAA-LTE, has been proposed in the 3rd Generation Partner Project (3GPP) Release 13. In the LAA technology, the unlicensed frequency bands are taken as secondary carriers by carrier aggregation, to participate in data transmission, thereby sharing load with the licensed frequency bands.
It is helpful for the operator to meet requirements of increasing capacity and to improve mobile wideband service, by expanding the LTE to the unlicensed frequency spectrum. In a region of dense data traffic, the LTE system may achieve high-speed data communication and a larger capacity using the unlicensed frequency spectrum, in a case of complementarily co-existing with a wireless local network.